Figure 1.

Recombinant hLM-521 is trimeric and adhesive in vitro. (A) Five nanograms of recombinant hLM-521 trimers were subjected to 4%–15% SDS-PAGE and detected by silver staining. The trimers (approximately 800 kD) were too large to migrate out of the well without reduction (lane 1) but separated into approximately 400-kD α5 chains and β2 and γ1 chains that comigrated at approximately 180–200 kD under reducing conditions (lane 2). (B) With a sandwich ELISA using anti-FLAG as a capturing antibody and anti-hLAMC1 as a detection antibody, hLM-521 showed a concentration-dependent (from 0.08 to 20 µg/ml) increase in OD at 450 nm. (C) K562 cells expressing integrin α3β1 were plated onto hLM-521–coated dishes and assayed for the number of cells adhered. Adhesion was specifically blocked by antibodies to integrin α3 and β1 but not by antibodies to integrin α6 or to Lu or by nonimmune mouse and rat IgG.